Insulated electrode for spark plugs



w. s. THOMAS.

INSULATED ELECTRODE FOR SPARKEEUGS APPLICATION FILED JUNE 27.1921.

1,437,999, Patented D60. 5, 1922.

Patented Dec, 5, 1922.

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wILLIAIvI- s. THOMAS; 0E LINDEN, nEw JERSEY, AssIeNoEmo" 'rnoiims sra aif rim coniPAnmoE ROSELLE PARK, NEW JERSEYI INSULATED ELECTRODE FOR SPARK PLUGS;

, Application filed June 27, 1921. Serial No.480',913.-

To all whom it may concern: Be it known that I, -WILL IAM S. THOMAS,

a citizen of the United States, residing at One object of my invention is to provide an improved insulated electrode for spark plugs which will keep cooler while func tioning in an internal combustion engine than insulated electrodes used prior to my present invention. plish by a novel construction which allows an open air space surrounding the positive electrode wire as far as possible towardthe end or nose ofthe insulating core which enters the combustion-chamber, thereby allowing a circulation of air at all times within said insulating core and aroundsaid POSI- tive electrode wire. I

Another object is to providefia structure which will prevent the establishment of an excessive pressure even though any minor leak should be effected by or through the web of the insulating core.

It is a well known fact to those skilled in the art that cement as generally ap-- plied in spark plugs has undesirable effect on the electrode structure and cannot be depended upon ordinarily to provide permanent joints and seals when subjected to the conditions imposed upon spark plugs.

Another and very important object of my invention is to provide improved means of simple and durable construction for securing the electrode wire to theinsulatingcore or shell; the same being rendered possi-.

ble without the use of cement;

A further object is to provide in connection with the insulat-ingcore or shell, a readily removable cap, the removal of which allows the connecting of the high tension lead to the electrode wires within the core and should the insulator be broken. down above the shoulder or thickest portion of the insulating core, the spark will be visible and hence the structure does not require the use of a delicate or technical appliance to determine whether the plug is in good working condition.

These objects, and other advantageous ends which will be described hereinafter, l attain in the following manner, reference This object I accoIn being had to the. accompanyingldrawings' in which Flgure 1 is an elevationahview of an 111 sulated elect-rode made. in accordance with my present invention,

Figure 2 is an enlarged section: takenlon the line 2-2 of Figure 1',

Figure .3 is a bottom. plannview of F igure 2, and l Y Flgures 41 to 7 inclusive are enlargedfragmentary elevations showing: slight modifications in the construction of the; securing. means of the electrode wire to the core or insulator shell.

Referring toth'e drawings-, .8"represents an.

insulating core which may .be made of any suitable electrode insulating material and v includes a body portion 9 which is exters nally screw threaded at its upper end, as shown at 10, and acap 11- which has internal screw threads 12 sothat the-cap can be screwedon the body portion 9;; said; cap including a chamber'l3 positioned di re'ctly above thetop of the bodyportion9;. This cap has radially disposed. holes or perforations 14 whichcommunicate with: the-- atmosphere and also with the chamber 13 permitting air to pass into and out of! the chamber 13 as will be more fully described hereinafter. The body portion 9" hasaniseli larged external shoulder or flange 15 which is positioned, above its lower end, ornose 16; Furthermore the body portion-9 has a cylindrical cavity 17 extending; axially,- and downward'from the top surf-ace 18 of the body portion 9; This cavity terminatesin a lower shoulder 19. and a counter cavity 20- of smaller diameter thanthe cavity 17,

leads downwardly from the: shoulder 19 and forms thetop of a transversely extending web 21;;- said web being formed integral with the other part of the core body 9 A; recess or cavity 22 extends upwardly and axially from the bottom surface 23' of the; insulator nose 16, and the upper wall of, this recess22 provides the bottom of the web 21. An auxiliary insulating; tube 24, preferably of mica, fits the cavity 17 the lower edge of the mica tube resting on the shoulder 19; the internal diameter of said: mica tube 24 preferably being larger than the diameter of the counter-cavity 20;.

, Referring particularly to Figure 2-,, an electrode wire 25 has a screw threaded portion which extends through a central hole 26 in the web 21 of the insulator; a part of this screw threaded portion of the electrode wire 25 extending upwardly into the space within the mica tube 24 and another part of this screw threaded portion of the electrode wire extends below the web 21 and upon this latter part of the screw threaded portion of the electrode wire is screwed small nut 27 which abuts the under surface of the web 21. The diameter of the electrode wire 25 is small compared to the diameters of the coun ter cavity 20, recess 22 and internal diameter of-the mica tube 24 so that there is a coinparatively large air space existing between the electrode wire and the inner surface of the mica tube 24. A second nut 28 is screwed on the upper portion of the electrode wire and abuts the top surface of the web 21 so that the web 21 is clamped between the nuts 27 and 28'.

In assembling the parts, the nut 27 can be screwed downwardly on the threaded portion of the electrode before the electrode is inserted through the hole 26, after which the upper portion of the electrode can be inserted upwardly through the hole 26 and a small nut-carrying wrench can be inserted downwardly through the tube 24 to apply the nut to the top end of the threaded por tion of the electrode wire and the nut 28 can be screwed downwardly into firm clamping engagement with the top of the web 21; it being noted that sufficient space is provided between the sides of the nuts to permit said small wrench to enter the space between the nut 28 and the side wall of the counter cavity20.

The cap 11 has a metallic head secured thereto and in the present instance I have illustrated the head 29 including an enlarged flange 30, which abuts the uppermost surface of the chamber 13, and an angular portion 31 which may be embedded in the material of the cap so as to prevent rotation between the head 29 and the cap. The head 29 includes an upwardly extending screw threaded stem 32 to which a thumb nut 33 is secured and I have also illustrated two other nuts 34 screwed on said stem and between these nuts and the thumb nut the usual electric wire can be clamped and connected.

- An electric conducting member 35 depends rigidly from the head 29 and in the present instance I have illustrated this member in the form of a metallic tube which extends downwardly through the chamber 13 and the chamber provided by the space within the mica tube 24:; this tube 35 being of smaller external diameter than the internal diameter of the mica tube 24 so that there is an air space entirely surrounding the metallic tube 35. The lower end of the metallic tube 35, when the cap 11 is screwed on the body portion 9, is adapted to engage over the nasaeee top portion of the electrode wire 25 and make electric contact therewith. I prefer to slot the lower end of the tube 35 so as to make the same slightly resilient and capable of slightly yielding so as to pass over the top of the electrode wire and then resiliently move into firm fitting engagement with the electrode wire. It will be noted that air is free to circulate through the perforations 14, chamber 13 and chamber 36 and in this man ner the adjacent parts are kept cool during use of the device. In addition to this, it will be noted that the air chamber 36 extends continuously from a position above the shoulder 15 to a position below the shoulder 15 and since this shoulder is the part em ployed for connecting the insulated electrode to the metallic shell (not illustrated) of the spark plug there is practically no possibility of transverse current leakage or short-circuiting. Thus with this construction 1 am enabled to increase to a very high degree the likelihood of maintaining the dielectric strength of the insulator and to eliminate electrical leakage through conduction at or about the shoulder or thick portion of the insulator. I

Furthermore by employing the structure as noted it is unnecessary to use objectionable cement, filled gaskets or the like and yet a lasting sealed structure is provided.

While I prefer to employ two nuts on the electrode wire for engaging opposite surfaces'of the web 21 of the insulator body, nevertheless if desired I may modify this structure in slightly different forms as illustrated in Figures 1 to 7 inclusive.

In Figure 4, I have shown a structure wherein I retain the separate nut 28 but secure the lower nut directly to the electrode wire as shown at 27 or therefore this nut 27 may be in the form of an integral part of the electrode wire.

In Figure 5, I have shown a reversal of the structure shown in Figure 1 wherein I retain the separate nut 27 and make the nut 28 a fixed part of the electrode wire and therefore this part 28 may be an integral portion of the electrode wire.

In Figure 6, I have shown a structure in which both of the nuts 28 and 27 are fixed to the electrode wire and therefore may be integral parts of said electrode wire. With this construction it would be necessary to apply a compression force to move the parts 28 and 27 into firm clamping position with the web 21 of the insulator.

In Figure 7, I have illustrated a form identical with that shown in Figure 2 with exception that I have illustrated washers or gaskets 37 between the nuts and the web 21. It will be noted that the parts can be readily assembled and disassembled and if it is necessary at any time to replace the auxiliary mica tube the same can be done by removing the cap and the mica tube and then be pulled out of position and replaced by a new one.

While I have described my invention as taking a particular form, it will be understood that the various parts of my invention may be changed without departing from the spirit thereof, and hence I do not limit myself to the precise construction set forth, but

consider that I am at liberty to make such changes and alterations as fairly come within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by. Letters Patent is Y 1. An insulated electrode including an insulating core providing a cavity and a Web extending transversely of said cavity and including a hole; an electrode Wire extending through said hole and into said cavity; means on said wire for clamping engagement with opposite portions of said web whereby the electrode wire is positively secured to the insulating core, said insulating core including a cap detachably secured thereto; and an electric conducting member secured to said cap and adapted to engage said electrode wire within said cavity; substantially as described.

2. An insulated electrode including an insulating core providing a cavity and a web extending transversely of said cavity and including a hole; an electrode wire extending through said hole and into said tion for fitting over said electrode wire;

substantially as described.

3. An insulated electrode including ian insulating core body having acavity extendv ing downwardly therethrough; an auxiliary insulating tube' fitting said cavity; an electrode having a portion extending upwardly into said cavity; a cap detachably secured to said body and having a conducting portion secured thereto and adapted to extend into said cavity and engage said electrode, said body having a portion below said tube and through which said electrode extends; and means on said electrode for clamping engagement with opposite sides of said lat ter portion; substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing Witnesses. i

' Witnesses:

ELIZABETH GARBE, CHAS. E. Poms;

WILLIAM s. THoMAs. 

